ABSTRACT
AIM: Carry out comparative analysis of survival of typical strains and genovariants of V. cholerae biovar El Tor imported in different years to the territory of Russian Federation, in the absence of nutrients and under the conditions of temperature stress. MATERIALS AND METHODS: 24 V. cholerae biovar El Tor strains isolated in 1970 - 2011 were studied, 8 of those were typical isolates and 16--genetically altered variants. Strain survival was studied in 0.9% sodium chloride solution and autoclaved river water at various temperature modes (5, 25, 37 and 42 degrees C). Protein composition and exopolysaccharide production were determined by electrophoresis method by U.K. Laemmli. RESULTS: Genovariants as well as typical strains were shown to be able to exist for a long time (up to 5 months) in the absence of nutrients at the temperature of 25 degrees C. However, unlike typical eltor vibrios, genovariants were more resistant to temperature stress. As a result of adaptation to high temperature (42 degrees C) biosynthesis of porin proteins of outer membrane OmpU and/or OmpT is increased in genovariant cells, and at lower temperatures (5 degrees C)--exopolysaccharide. CONCLUSION: V. cholerae biovar El Tor genovariants are able to adapt to temperature change better, that may facilitate their higher survival in the environment.
Subject(s)
Adhesins, Bacterial/genetics , Bacterial Proteins/genetics , Genes, Bacterial , Polysaccharides, Bacterial/biosynthesis , Porins/genetics , Vibrio cholerae/metabolism , Adaptation, Physiological/genetics , Adhesins, Bacterial/biosynthesis , Bacterial Proteins/biosynthesis , Culture Media , Electrophoresis, Polyacrylamide Gel , Gene Expression , Humans , Mutation , Polymerase Chain Reaction , Porins/biosynthesis , Russia , Stress, Physiological , Temperature , Vibrio cholerae/genetics , Vibrio cholerae/isolation & purificationABSTRACT
The molecular-genetic peculiarities of the prophage CTXφ genome, the VPI-1 pathogenicity island, and the VSP-II pandemicity island in recently emerged, genetically altered Vibrio cholerae El Tor strains have been studied. The genome of the prophage CTXφ, which contains the ctxAB operon, which codes cholera toxin (CT), was shown to be unstable. A comparative analysis of the nucleotide sequences of the two phage genome regions (the ctxB gene and ctxAB operon promoter region) among 23 genovariant strains allowed us to reveal the presence of distinct ctxB gene alleles (ctxB1 or ctxB7) that differed in single-nucleotide substitutions and the polymorphism of the ctxAB operon promoter region. An analysis of the VPI-1 structure showed that tcpA gene that encodes the basic protein of the toxin-coregulated pilli (TCP) was represented in the genovariants by four alleles. The variability of the VSP-II was also revealed. It was manifested in the occurence of the deletions of varying length (2069 or 13 105 bp).
